21121221200 has 120 divisors (see below), whose sum is σ = 52110801600. Its totient is φ = 8223713280.

The previous prime is 21121221193. The next prime is 21121221221. The reversal of 21121221200 is 212212112.

It is a super-2 number, since 2×21121221200² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2426456 + ... + 2435144.

It is an arithmetic number, because the mean of its divisors is an integer number (434256680).

Almost surely, 2^21121221200 is an apocalyptic number.

21121221200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21121221200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26055400800).

21121221200 is an abundant number, since it is smaller than the sum of its proper divisors (30989580400).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21121221200 is a wasteful number, since it uses less digits than its factorization.

21121221200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8869 (or 8858 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21121221200 its reverse (212212112), we get a palindrome (21333433312).

The spelling of 21121221200 in words is "twenty-one billion, one hundred twenty-one million, two hundred twenty-one thousand, two hundred".